TP going down and down

Been using Xert a good while now, it was working really well, TP rising nicely etc. Recently my training has been a bit sporadic, though getting more regular now and I’m sustaining 2 stars - fine for me. For the past few months my TP has been on a constant downward trend, dropping 1W or so each day. This doesn’t seem to reflect my fitness, which seems to be increasing. It’s got to the stage where I can do a Hardness Test 16 without issue, and I am definitely nothing like the ‘exceptional athlete’ referred to in the workout description. I can think of a couple of reasons why:

  • I’m pretty time poor so often only have an hour in an evening, and if I’m up top it I’ll knock out a 1 hour workout with the max XSS I can. I do a couple of hours one or both days at the weekend.
  • I’m regularly in training deficit, sometimes quite a bit if I miss 2 or 3 days training in a row - I’m getting back on track now but it’s taken a while
    I also don’t have any events planned, not sure if that has anything to do with it.

All ideas welcome.

Hi Scott,

I took a look at your progression to get a better idea for what you’re talking about. Is your peak power underestimated by chance?
The system generally tracks your TP, HIE, and PP along with the low, high, & peak training loads, meaning that the more you strain you place on those systems, expects an upward trend in your fitness signature. We also decided to decay the parameters gradually over time. This makes it more likely that we will detect a breakthrough in the future. This is why we recommend aiming for a breakthrough activity every few weeks.

Thanks very much Scott. It’s perfectly possible that my peak power is underestimated. I’m sure it’s obvious but is there a PP estimation workout?

I’ve been getting breakthroughs pretty regularly, last one was a week ago. And I had a flurry a couple of weeks ago pracically every workout (repeated Hardness Tests as described). TP still went down as usual!

Maybe it’s a combination of me only doing Hardness Tests for a while and an underestimate of PP?

I’m all ears regarding a way to ‘reset’ and get back on track.


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Do you have power on your bike for outdoor rides too? Next time you’re outside, try and throw down as much power as you can for ~10s. This will give Xert a good idea for what your PP should be. We also have a variety of “fitness tests for breakthroughs” in the workout library. This should help the system identify a more “correct” signature, but feel free to use any maximal effort (hard workout, local club ride, a Strava segment PR attempt, Zwift race, etc.). Hope this helps!

Thanks, no power on outdoor bike unfortunately but I’ll see what I can do via a workout or Zwift or something. If I’m not successful I might have to come back to you, hope that’s ok.

Be sure to record any non-power activities with HR and cadence data. We’re working on something to address non-power rides, but it will require that data. You can always contact our support staff about questions as well. Cheers!

Scott, thanks very much. Sounds good. I didn’t actually realise there was a separate ‘support line’. You’ve been a great help, cheers.

What’s the plan with HR data?

We’re working on something to assist with calculating XSS and Focus for rides that are completed without power data.

Scott, quick update. I signed up again to Zwift to do a peak power run - no power meter on outdoor bike so had to use the turbo. Xert now showing my PP at 951W, up just over 300W from what Xert showed yesterday. I hadn’t done anything PP related for ages.

Do you think that will do it with regards to getting a more reflective fitness signature, or do you advise doing something else? I’m going to throw in something like ‘Xert Fitness Test for Breakthroughs - Under Pressure’ regularly, partly because I enjoy those kinds of things.

Suggestions welcome. Thanks again for all the good work.

Hi Scott,

Missed your last update here, but I’ll follow up now. A severely under reported PP can have a negative influence on your overall fitness signature (typically manifests in an overestimated TP and underestimated HIE). Have you noticed that your power duration curve was more representative of your abilities after getting a more accurate PP?

Hi, sorry for the delay. I didn’t notice anything particularly changing after the Zwift session that resulted in the increased PP. Couple of reasons:

  1. My traiinng has still been a bit spotty over the last couple of weeks, ramming in a Hardness test then missing a couple of days… I will get it back on track next week so hopefully that will start to improve things. I just finished a Level 13 and it was still pretty comfortable (a good workout but in no way a beasting, which I’d expect it to be).
  2. I’m not familar with the power duration curve - where do I see that? Sorry if that’s a dumb question. I have explored the Progression tab reasonably.

If you open your last activity, you’ll find a tab called “Power Duration”. It will give you a curve that look similar to this:

The red line represents your mean max power (MMP) from the ride at various durations, while the blue line shows the highest possible MMP you could achieve based on your signature. Make sure that the blue line looks similar to the power that you’re able to actually achieve at those durations.

Hardness test level 13 is quite difficult to complete, so you’re either comfortable with suffering (difficulty of 170 is tough), or your fitness signature might be a little underestimated. To verify your signature, you could try aiming for a breakthrough - we have a few fitness tests/breakthrough workouts in the library, or push yourself as much as you can in a Zwift race, etc.

Got it thanks, that’s really helpful. I’m most certainly no superstar so I expect the signature is still underestimated. I’ll go for some breakthroughs. Also, would doing a workout and manually upping the difficulty with the up button on my Garmin ‘re-educate’ Xert?

Increasing the difficulty might force a breakthrough on a sufficiently difficult workout, but I wouldn’t recommend it. I would instead do a Zwift race, aim for a PR on a local Strava segment (if you can still ride outside), or try one of the breakthrough workouts on Xert.

Another one of my favorite “freestyle” breakthrough activities are 30/15’s… with your trainer in slope mode, do 30s of all-out riding with 15s recovery. Repeat 13 times in a set, and aim to perform 3 sets. It’s highly taxing, so aim to do these only when you’re fresh & motivated. These are very helpful for Xert to detect an accurate HIE and TP - notice the large amount of time spent very near MPA in the first set below. The result may look something like this:

Got it, thanks Scott. I’ll do the 30/15s.

I might look at a Zwift race - never done one, Zwift membership will run out again early Nov, prefer to give Xert my money :slight_smile: